The present invention relates to an assembly for converting the one-directional power transmission of a power ratchet wrench into alternating transmission of power in both clockwise and counter-clockwise directions. One embodiment of the tool is for scraping flat surfaces. More particularly the scraper tool of the present invention provides an oscillating actuated motion about a given axis. Even more specifically, the present invention is a specialized hand-held power tool for scraping flat surfaces such as gasket receiving surfaces of mating parts.
Existing scrapers are of three types. The traditional flat blade hand tool which has a handle along the same axis as the scraper blade. Pressure is applied to the handle in a forward moving direction and the flat blade, more particularly the scraping or cutting edge of the blade, rests against the surface to be scraped. As the cutting edge moves forward along the surface, a thin layer of material on the surface is removed. The operator may push forward or pull back slightly to engage and disengage the cutting edge from the leading edge of the cut to facilitate the removal of the thin layer. Generally, there is no side-to-side movement of the blade.
The second type of scraper is a power scraper which utilizes a reciprocating action, i.e., in and out, of a drive mechanism with a flat scraping blade affixed to the distal end of the driver. Again, the user applies a slight forward moving pressure to the handle of the drive, but the in and out reciprocating movement of the driver provides the cutting energy in the tool. There is no side-to-side or arcuated motion imputed to the cutting blade by the driver or the operator.
A third power-driven scraper utilizes a straight line reciprocating side-to-side motion and does not provide the arcuate movement provided by the present inventive scraper.
U.S. Pat. No. 3,604,520 (Shatto) teaches a power scraping tool with a blade having a ratchet means which prevents the work member and work blade from undergoing a return stroke. However, as will be seen, its operation is very different than the present invention.
U.S. Pat. No. 4,255,828 (Colla) shows the combination of a conventional socket wrench with a scraper attachment, but the operative scraping edge rotates about the same axis as the axis of the socket driver. Further the operative scraping edge of the attachment does not oscillate back and forth in an arcuate path as taught in the tool of the present invention.
Other power scraping tools are taught in U.S. Pat. No. 3,147,549; 3,377,702; and 4,413,412.
It has long been known that in using scrapers the cutting edge will jam or wedge into the flat surface being scraped or the material being removed. The operator will "wiggle" the tool slightly from side-to-side (left-to-right or right-to-left) in small arcs in order to free the cutting edge. Once freed the operator continues to stroke the tool forwardly to scrape the surface.
The scraper tool of the present invention provides a continuously oscillating arcuate movement of the blade as the tool is moved forward along the surface to be scraped. This arcuate movement is translated across a plane generally perpendicular to the axis of rotation of the driver head as held by the operator. Thus improved scraping efficiency is achieved with the present device. Further, one embodiment of the scraper tool of the present invention may be adapted for attachment to a conventional power ratcheting tool for converting the tool into one that provides a continuous oscillation of the ratchet mechanism which is translated into arcuate movement of the cutting blade of the tool.
Although a most practical application of the present invention focuses on a scraper assembly, it should be understood that the present invention converts the one-directional power transmission of a power ratchet wrench into a unit in which power is alternatingly transmitted to the attachment to the wrench in both the clockwise and counter-clockwise directions without switching back and forth the direction selector switch or subassembly of the wrench. Any attachment to a conventional power ratchet wrench which may be benefitted by transmission of rotational power in both directions could be adapted to use the present invention.
The present invention provides a new, special scraper attachment to the traditional line of accessories in the powered, hand tool product line, without the need for the introduction or purchase of a new driver.
This new attachment may be effectively utilized by engine mechanics to quickly clean gasket surfaces in hard-to-reach areas where previous tools have been ineffective. The tool of the present invention may be adapted to be connected to poppet valve heads to provide small alternating clockwise and counter-clockwise rotation of the valve head in its seat for use in valve lapping operations.
Thus the assembly of the present invention provides a solution to long-standing problems in the powered, hand tool industry by providing a highly efficient oscillating scraper.